The need to remove heat from gas streams arises in numerous applications. In motor vehicles, for instance, it may be necessary to remove heat from the intake and/or exhaust gas streams. For example, intake air (or “charge air”) requires cooling in some applications, for example in turbocharged or supercharged engines. In vehicles incorporating exhaust gas recirculation (EGR) or exhaust gas heat recovery (EGHR) systems, heat is removed from the exhaust gas stream. The heat removed from the intake or exhaust gas stream is typically transferred to a liquid coolant in a heat exchanger.
In motor vehicle exhaust applications, heat recovery devices are usually located in series with other under-vehicle exhaust components such as catalytic converters. Series arrangement of individual exhaust components is wasteful of space, may increase the cost and weight of the vehicle, and limits the ability to control the temperature of exhaust components upstream of the heat recovery device. The incorporation of a bypass flow path into the heat recovery device usually involves the addition of an external pipe to the exhaust system, and is yet another component which must be accommodated under the vehicle.
An example of an annular heat recovery device for use in an exhaust system of a motor vehicle is disclosed in US 2009/0038302 A1 (Yamada et al.), published on Feb. 12, 2009. While the Yamada et al. device provides a central bypass flow path and thereby eliminates the need for an external bypass, its installation downstream of the catalytic converter (FIG. 6 of Yamada et al.) fails to address the other issues noted above.
There remains a need for simple and effective heat recovery devices for motor vehicle intake and exhaust gas systems which minimize usage of space, weight, and number of components, and which provide enhanced opportunities for temperature control of other system components.